1. Field of the Invention
The present invention relates to the electronic production of audible sound and particularly to the exercise of control over electronic musical instruments of the keyboard type. More specifically, this invention is directed to electronic musical instruments having an audio signal generator and operated by means of the actuation of keys and other input mechanisms, such as stops, which maybe associated with switch contacts. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
Electronic musical instruments are well known in the art. Such instruments typically include a keyboard and additional input mechanisms, known generally as "stops", by which the musician may control the instrument. As used herein, the term "keyboard" is intended to include not only those input devices, i.e., manuals, which are actuated by the musician's fingers, but also to include pedal systems, button systems and other input members which are operated by the musician during the playing of the instrument. The term "stops" as used herein is intended to include those additional input devices by which control over a keyboard instrument is varied such as pull-rods, on-off switches, etc. which determine the tone color of the instrument and which are generally rarely operated during the playing of a particular selection.
An electronic musical instrument of the type generally described above is shown in published Germany Patent Application number 27 11 511. In such instruments the audio frequency signals which are to be delivered to a loudspeaker are digitally synthesized under the control of switch contacts opened and closed by the musician as he manipulates the input devices including the keyboard. In the prior art, the keyboard contacts are disposed in a first matrix while the contacts associate with the "stops" are disposed in a second matrix. The musician's "commands", as determined by the relevant switch positions, are determined by scanning circuits which periodically sense the state of the various switches and transmit the relevant information to associated signal processing circuits. A typical instrument may have two manuals, i.e., two finger responsive keyboards, each of which covers four octaves. The typical instrument may also have "stops" which enable the selection of over ten harmonics and numerous amplitude levels. In many cases, switches are also provided for fixed stops. The wiring of all of the various switches, particularly the numerous connections to the proper signal processing circuits, is a time consuming task. The inspection and servicing of such intricate wiring is also a difficult and time consuming task.